On Mar. 1, 2004, American Association of Blood Banks (AABB) standards mandated that United States blood centers commence testing all platelet units for bacterial contamination. This new standard was based on the significant risks to transfusion patients associated with contaminated platelet units. Approximately 4 million platelet units are transfused per year in the U.S., of which up to 4000 are potentially contaminated. Contaminated platelet units have been identified as a cause of sepsis-related morbidity and mortality. The room temperature storage requirement of platelets, which is essential for viability and function, also serves to facilitate bacterial growth. Even at early time points in the mandatory maximum five-day storage time limit post-collection, microbial growth may reach significant levels. Further, it may be desirable to monitor platelet units for fungal contamination in addition to bacterial contamination.
Furthermore, there exists no assay for direct detection of bacteria in urine for diagnosis of urinary tract infections (UTIs). Current methods instead diagnose UTIs indirectly by urinalysis, for example, by determining specifically the presence of nitrites, leukocytes, or leukocyte esterase and chemical testing for glucose or pH. Diagnosis of a UTI, if confirmed, is done so by bacterial culture, which can be laborious and time consuming. Similarly, there is no direct test for bacteria in cerebrospinal fluid available which could be used for the rapid diagnosis of bacterial meningitis, a rapidly progressing infection of the central nervous system which is typically fatal if antibiotic treatment is not initiated promptly. Culture methods are too slow to be of use in diagnosing such infections.
The need to detect bacterial and fungal contamination, however, is not limited to platelet units, urine, and cerebrospinal fluid. Bacterial and fungal contamination of many clinical, agricultural or environmental products may lead to severe illness, and even death, if contacted by a subject or administered to a subject. In addition to monitoring clinical products such as blood, plasma, platelets, and other bodily fluids such as urine and cerebrospinal fluid for bacterial and/or fungal contamination in a hospital or clinical setting, it is highly desirable to monitor wound dressings for contamination in remote or field locations. Also, there are increasing safety concerns to monitor both food products and the water supply for bacterial and fungal contamination. This concern may also apply to recreational facilities such as swimming pools and lakes, which may be contaminated with high levels of bacteria or fungi. Accordingly, there is an immediate and unmet need for detecting bacterial or fungal contamination in numerous products that are consumed or used by humans.
Many tests exist for sensitive detection of a broad spectrum of various bacterial species based on the detection of specific bacterial antigens. One limitation of these methods is that they cannot be applied directly for testing of samples where the spectrum of bacterial pathogens is unknown. There remains a need for the development of a test capable of detecting all bacteria present irrespective of species or strain.
Current tests for bacterial and/or fungal contamination involve complicated tasks requiring particular reaction conditions and often take days to complete. Another barrier to widespread acceptance of various tests for bacterial or fungal contamination is low sensitivity, low specificity, and high cost. For example, conventional culture methods require culturing or growing the bacteria on a petri dish and then determining the type of bacteria by Gram staining. This process can often take up to 72 hours. A quick and easy assay for detecting bacterial or fungal contamination is needed and as such would facilitate a ready supply of clinical, agricultural, and environmental products that are free of bacterial and fungal contamination and safe for use by humans.